Electromagnetic reversing switch



Aug. 14, 1951 w. G. BOURNE ELECTROMAGNETIC REVERSING SWITCHES Filed Dec.20, 1948 .Ilz/v elw/bop W.

Patented Aug. 14, 1951 LECTROMAGNETIC REVERSING SWITCH William GeorgeBourne, London, England, as-

signor to Rotax Limited, London, England Application December 20, 1948,Serial No. 66,272 In Great Britain January 3, 1948 1 Claim. l

This invention has for its object to provide an improved electromagneticreversing switch adapted more particularly for controlling a reversibleelectric motor, but applicable to other analogous uses.

In the accompanying drawings:

Figures 1 and 2 are respectively sectional side view and plan of aswitch embodying the invention.

Referring to the drawings, I mount on any convenient base a a pair ofelectrcmagnets b, these being arranged parallel with each other (orotherwise side by side) and at a convenient distance apart. Between theelectromagnets are mounted a pair of fulcrum pieces c, these being alsosituated at a convenient distance apart.

Each such piece consists of an iron plate bent to an L-shaped form, onepart of which being arranged beneath and secured to the lower end of thecore of the associated electromagnet and the other part being arrangedto extend upwardly alongside the electromagnet. On the upper ends of thetwo fulcrum pieces is supported an iron rocker d which extends acrossthe upper ends of the cores of the electromagnets. Transversely acrossits centre the rocker is shaped to the form of a shallow trough, whichlies between the upper ends of the fulcrum pieces c, and in the troughis located a T-shaped retaining piece e the head of which lies in thetrough and the stem of which extends through the rocker and a bridgepiece f between the fulcrum pieces, a loading spring g carried on thestem serving to hold the rocker on the fulcrum pieces.

On each of the two arms of the rocker is secured an insulating piece ILto which is attached a pair of contact members i. Each of the latter isof T-shape and its head is provided with a pair of contact pieces :i (ora single contact piece) which can bridge a pair of xed contact pieces kcarried on the base. The tail of each contact member extends towards thecentre of the rocker, and the adjacent ends of one pair of oppositecontact members may be interconnected by a short flexible conductinglink m. Each contact member is attached to its insulating piece by ascrew n through the medium of a small spring o and moreover is supportedon the said piece by a pair of pivot points p, so that the contactmembers can rock slightly about a longitudinal axis and thereby ensureuniform pressure on the associated pair of fixed contact pieces when theswitch is closed.

It will be understood from the foregoing that on the base are providedfour pairs of fixed contact pieces, and that each arm of the rockercarries two movable contact members, one of which can bridge one pair ofxed contact pieces and the other can bridge the other pair. The xedcontacts are suitably interconnected to enable the required reversal of.current ow to be obtained, and when the switch is required for use witha reversible electric motor having shunt and series field windings, aterminal is provided on one of the interconnected movable contactmembers for connection to one end of the shunt winding.

The switch construction is such that when either of the electromagnetsis excited it pulls down the adjacent end of the rocker, causing thelatter to rock on one of the fulcrum pieces against the action of thespring of the retaining member, the rocket being in this action liftedoff the other fulcrum piece. On release of the rocker by theelectromagnetic, returns under the action of the said spring to itsoriginal position where it is supported on both of the fulcrum pieces.

When the switch is used to control a reversible motor of the kind abovementioned, the motor armature is connected to one in each pair of fixedcontact pieces at one end of the switch, and the power supply isconnected to terminals at the other end of the switch, the series fieldwinding being connected between one of these terminals and one of theadjacent xed contact pieces, and the other terminal being connected toanother of the xed contact pieces at that end. Also the shunt iieldwinding is connected between one end of the series field winding and oneof the movable contact members, the various connections being such thaton moving the rocker to one position or the other from its central oroff position, the reversal of the direction of current occurs only inthe motor armature.

A switch as above described serves not only as a reversing switch butalso as a controlling switch, as it automatically interrupts the currentsupply when either of the previously operative electromagnets is put outof action, the latter being under the control of a manually operableswitch or switches.

By this invention I am able to provide an electromagnetically operablereversing switch ina very convenient form, and although the switch isprimarily intended for controlling a reversible electric motor, it maybe applied to other analogous uses.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is: i

An electromagnetic reversing switch, comprisaeeaeee electromagnets, apair of spaced fulcrum pieces situated .between the electromagnets andsupporting the rocker at opposite sides of its centre. the central partof the rocker being shaped to form a shallow transverse trough whichlies between adjacent ends of the fulcrum pieces, spring loadedretaining means arranged centrally between the fulcrum pieces and havinga part located in the trough to hold the rocker on the fulcrum pieces,movable contacts carried by the rocker, and fixed contacts with whichthe movable contacts cio-operate under the action of the rocker.

REFERENCES errar The following references are of record in the file ofthis patent:

I UNITED STATES PATENTS Number Name Date 799,016 Schwarze Sept. 5,19051,019,484 Kennedy Mar. 5, 1912 1,422,523 Beach July 11, 1922 1,562,646Kaisling Nov. 24, 1925 1,991,037 Werner Feb. 12,1935 2,082,493 l HartmanJune 1, 1937 2,315,920 Baker et al Apr. 6, 1943 2,431,025 Buell Nov. 18,1947 2,436,224 Ogle Feb. 17, 1948 2,448,772 Clare et al Sept. 7, 1948

